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netfilter: nf_conntrack_h323: Add protection for bmp length out of range 

JIRA: https://issues.redhat.com/browse/RHEL-33469
Upstream Status: commit 767146637efc

commit 767146637efc528b5e3d31297df115e85a2fd362
Author: Lena Wang <lena.wang@mediatek.com>
Date:   Tue Mar 5 11:38:55 2024 +0000

    netfilter: nf_conntrack_h323: Add protection for bmp length out of range

    UBSAN load reports an exception of BRK#5515 SHIFT_ISSUE:Bitwise shifts
    that are out of bounds for their data type.

    vmlinux   get_bitmap(b=75) + 712
    <net/netfilter/nf_conntrack_h323_asn1.c:0>
    vmlinux   decode_seq(bs=0xFFFFFFD008037000, f=0xFFFFFFD008037018, level=134443100) + 1956
    <net/netfilter/nf_conntrack_h323_asn1.c:592>
    vmlinux   decode_choice(base=0xFFFFFFD0080370F0, level=23843636) + 1216
    <net/netfilter/nf_conntrack_h323_asn1.c:814>
    vmlinux   decode_seq(f=0xFFFFFFD0080371A8, level=134443500) + 812
    <net/netfilter/nf_conntrack_h323_asn1.c:576>
    vmlinux   decode_choice(base=0xFFFFFFD008037280, level=0) + 1216
    <net/netfilter/nf_conntrack_h323_asn1.c:814>
    vmlinux   DecodeRasMessage() + 304
    <net/netfilter/nf_conntrack_h323_asn1.c:833>
    vmlinux   ras_help() + 684
    <net/netfilter/nf_conntrack_h323_main.c:1728>
    vmlinux   nf_confirm() + 188
    <net/netfilter/nf_conntrack_proto.c:137>

    Due to abnormal data in skb->data, the extension bitmap length
    exceeds 32 when decoding ras message then uses the length to make
    a shift operation. It will change into negative after several loop.
    UBSAN load could detect a negative shift as an undefined behaviour
    and reports exception.
    So we add the protection to avoid the length exceeding 32. Or else
    it will return out of range error and stop decoding.

    Fixes: 5e35941d99 ("[NETFILTER]: Add H.323 conntrack/NAT helper")
    Signed-off-by: Lena Wang <lena.wang@mediatek.com>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Signed-off-by: Florian Westphal <fwestpha@redhat.com>
This commit is contained in:
Florian Westphal 2024-04-22 11:26:34 +02:00
parent 4a57e93a55
commit 7db958545a
1 changed files with 4 additions and 0 deletions
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4
net/netfilter/nf_conntrack_h323_asn1.c
View File

@ -533,6 +533,8 @@ static int decode_seq(struct bitstr *bs, const struct field_t *f,
/* Get fields bitmap */
if (nf_h323_error_boundary(bs, 0, f->sz))
return H323_ERROR_BOUND;
if (f->sz > 32)
return H323_ERROR_RANGE;
bmp = get_bitmap(bs, f->sz);
if (base)
*(unsigned int *)base = bmp;
@ -589,6 +591,8 @@ static int decode_seq(struct bitstr *bs, const struct field_t *f,
bmp2_len = get_bits(bs, 7) + 1;
if (nf_h323_error_boundary(bs, 0, bmp2_len))
return H323_ERROR_BOUND;
if (bmp2_len > 32)
return H323_ERROR_RANGE;
bmp2 = get_bitmap(bs, bmp2_len);
bmp |= bmp2 >> f->sz;
if (base)